Advanced Technology Laboratories Research Articles

The architecture of HORNET: A packet-over-WDM multiple-access optical metropolitan area ring network

To cost-effectively address the phenomenal demand for bandwidth in the metropolitan area, the Optical Communications Research Laboratory at Stanford University and Sprint Advanced Technology Laboratories have developed a novel architecture for a large-scale metropolitan area network (MAN). The network, which is called HORNET, is a packet-over-WDM multiple-access network featuring the use of fast-tunable transmitters and a novel “CSMA/CA” media access protocol to improve network efficiency well beyond that of today’s solution. This paper presents the design and implementation of the network architecture and gives an analytical discussion of its advantages.

Potential of a hand-held ultrasound in assessment of the injured patient

Current studies indicate that portable ultrasound used by trained trauma surgeons in the emergency room can be performed using the focused abdominal sonogram for trauma technique in approximately 2 minutes to evaluate patients with blunt torso trauma. It has been shown to be as accurate as DPL and computed tomography (CT) in the detection of hemoperitoneum following abdominal trauma. It is also very accurate in detecting pericardial fluid and may have a role in the evaluation of penetrating injuries of the thorax, either from stab or gunshot wounds. The examination is best performed early on in the secondary survey of the injured patient. Miniaturization and hand-held ultrasound units are on the horizon. The faculty of the University of Washington in Seattle in conjunction with the Advanced Technology Laboratories in Seattle and the Advanced Research Project Agency of the Department of Defense are producing a battlefield hand-held ultrasound with the ultimate goal to have an ultrasound unit that will fit in the trauma surgeon's pocket. With the use of this new technology, the potential for early diagnosis of victims of trauma and prompt treatment is at hand. One of the greatest challenges remaining is that of training surgeons in the use of ultrasound. The author's experience in conducting ultrasound courses for surgeons at the Uniformed Services University of the Health Sciences is described.

Potential of a Hand-Held Ultrasound in Assessment of the Injured Patient

Current studies indicate that portable ultrasound used by trained trauma surgeons in the emergency room can be performed using the focused abdominal sonogram for trauma technique in approximately 2 minutes to evaluate patients with blunt torso trauma. It has been shown to be as accurate as DPL and computed tomography (CT) in the detection of hemoperitoneum following abdominal trauma. It is also very accurate in detecting pericardial fluid and may have a role in the evaluation of penetrating injuries of the thorax, either from stab or gunshot wounds. The examination is best performed early on in the secondary survey of the injured patient. Miniaturization and hand-held ultrasound units are on the horizon. The faculty of the University of Washington in Seattle in conjunction with the Advanced Technology Laboratories in Seattle and the Advanced Research Project Agency of the Department of Defense are producing a battlefield hand-held ultrasound with the ultimate goal to have an ultrasound unit that will fit in the trauma surgeon's pocket. With the use of this new technology, the potential for early diagnosis of victims of trauma and prompt treatment is at hand. One of the greatest challenges remaining is that of training surgeons in the use of ultrasound. The author's experience in conducting ultrasound courses for surgeons at the Uniformed Services University of the Health Sciences is described.

Preoperative color-doppler assessment of vascularisation of the rectus abdominis: anatomic basis of breast reconstruction with a transverse rectus abdominis myocutaneous flap A prospective study

The unipedicled TRAM flap is an useful alternative to breast reconstruction after mastectomy in patients who refuse mammary implants. There is however the risk of unpredictable partial skin necrosis even after rigorous surgical procedures. Certain authors have proposed color flow doppler assessment before reconstructive surgery better to identify the vascular network and optimise patient selection. We performed a prospective study in 20 outpatients in order to compare preoperative assessment of the blood supply to the abdominal flap with the operative findings. An Ultramark 9 HDI (Advanced Technology Laboratories) equipped with a high frequency (10 Mhz) linear probe was used to measure blood flow and vessel caliber in the epigastric a. and perforating vessels (localisation, number; peak flow). Despite three limiting factors (anatomic, technical, morphologic) the results obtained in this series could be used to determine the indications for a TRAM flap.

Duplex scanning in the postoperative surveillance of patients undergoing total hip arthroplasty

Color flow duplex imaging is a well-established method for the diagnosis of deep vein thrombosis in symptomatic patients; however, the sensivity and specificity of duplex scanning compared with venography in high-risk asymptomatic patients are not known. Consecutive patients undergoing total hip arthroplasty who consented to have bilateral venography on days 8 to 12 were included in this prospective study. One hundred and fifty-one venograms were finally obtained in 78 patients. All duplex scanning was performed with the Ultramark 9 ATL (Advanced Technology Laboratories) by one investigator. In the beginning of the study, the first 44 legs, only the femoropopliteal segment was tested and the result was based on B-mode compression; the sensitivity for the duplex was 56% ( 5 9 ), and the specificity, 94% ( 33 35 ). In the next 107 legs, the addition of color to our criteria improved the sensitivity of the duplex scan from 55% to 93% ( 13 14 ) for the femoropopliteal segment and the specificity from 94% to 99% ( 92 93 ). For the calf segment, in the same 107 legs, using the color facility of the duplex, the sensitivity and specificity were 79% ( 15 19 ) and 97% ( 85 88 ), respectively. The color facility of new-generation machines makes duplex scanning reliable for the detection of proximal deep vein thrombosis, even in asymptomatic high-risk patients. For the detection of calf deep vein thrombosis, however, more experience is needed. A larger study is necessary to confirm these preliminary data.

RASSP Enterprise Technologies for SignalProcessor Life-Cycle Support

Enterprise integration technologies are a key contributor to improving time-to-market, cost, and design quality by a factor, which is the goal of the DARPA Rapid Prototyping of Application-Specific Signal Processors (RASSP) program [1]. The Lockheed Martin Advanced Technology Laboratories (ATL) RASSP team developed a productivity improvement model, shown in Fig. 1, that indicates the relative contributions of various RASSP technologies to the overall improvement. Enterprise technologies address the entire 17% enterprise partition, and more than half of the 30% reuse and model-year architecture partition, thus accounting for at least 35% of the overall RASSP productivity improvement. The ATL RASSP approach to implement enterprise systems is to extend commercial technologies so the results are available to a broad base of potential users. Unlike current automation concepts which start at later stages of the development cycle, the RASSP enterprise system supports the entire signal processor life cycle. Core concepts of the enterprise system include: Tools and tool frameworks integrated into an enterprise environment Program execution control through workflows Integrated data management functions Design reuse Concurrent engineering team support Integrated design engineering and manufacturing. The model-year architecture, which enables users to rapidly, efficiently upgrade systems with new technology, is supported in the enterprise system by a robust reuse management system. Manufacturing interface and communication services elements of the enterprise system provide improved concurrent engineering support for distributed product teams. The enterprise system will be provided to commercial and aerospace users as products, including a reusable set of workflows for electronics design, commercial tools supporting the enterprise system environment, and utilities to enable users to customize the RASSP enterprise system for a particular organization or project. The enterprise system development cycle includes four build cycles with increasing capabilities. The ATL team completed the Build 2 implementation in May‘96. This implementation supports the processes associated with detailed hardware/software design, architecture design, and trade-off analyses. It is being used at Lockheed Martin and multiple government sites for benchmarking and evaluation. Results to date indicate >5:1 productivity improvements in the manufacturing interface, and 5–10% improvements in design engineering, which is growing with increasing level of utilization.

Rapid Prototyping of Application-SpecificSignal Processors (RASSP) In-Progress Report

The goal of the DARPA/Tri-Service-sponsored Rapid Prototyping of Application-Specific Signal Processors (RASSP) program is to reduce the cost and time to develop and manufacture signal processors by at least a factor of four. Lockheed Martin Advanced Technology Laboratories‘ (ATL) approach to reaching this goal is based on three thrusts: methodology, model-year architecture, and infrastructure (enterprise). The Advanced Technology Laboratories‘ RASSP team—composed of an alliance of companies—implemented the first baseline RASSP system, which advances today‘s state-of-the-art by a factor of >2X. The Advanced Technology Laboratories‘ RASSP team used the methodology and tools to demonstrate cost and design-cycle improvements on the benchmark virtual proto-type, and developed a hardware/software system that demonstrated first-pass success. Additional developments underway will provide further benefits and will demonstrate 4X improvements in cost and time to market. This paper updates the team‘s progress halfway through the program, and highlights the impact of using the RASSP concepts on the design of a SAR processor, a Navy standard processor upgrade, and a CNI application.

Model-Year Architectures for Rapid Prototyping

The Rapid Prototyping of Application-Specific Signal Processors (RASSP) program is changing the way engineers design embedded signal processors by providing a process that will reduce by at least a factor of four both the time-to-market and cost, and improve design quality. To achieve these improvements, Lockheed Martin's Advanced Technology Laboratories (ATL) is using a methodology that stresses hardware and software reuse, and model-year architectures that enable interoperability and upgrades through open interface standards. This paper describes ATL's model-year architecture, which defines a framework for reuse to enable low-cost technology upgrades for embedded processors. This approach can be applied to a wide range of military and commercial applications.

Interobserver Variability of Left Ventricular Measurements in a Population of Predominantly Obese Hypertensives Using Simultaneously Acquired and Displayed M-Mode and 2-D Cine Echocardiography.

Achieving low interobserver variability is a goal of echocardiographic determined left ventricular (LV) mass measurements. In a group of hypertensives, we evaluated interobserver variation using a method of simultaneously acquired two-dimensional (2-D) cine and M-mode images displayed in a split screen format. Sixty echocardiographic images from ongoing hypertension trials, including serial studies of the same patients, were obtained with an UltraMarktrade mark 6 Ultrasound System (Advanced Technology Laboratories, Inc., Bothell, WA, USA). Images were digitized online, coded with a random number, and pooled prior to the analysis to minimize observer bias. Studies were read by two independent observers in a blinded fashion and in a random order using a Color Vue II Nova MicroSonicstrade mark analyzer (Nova Microsonics, Mahwah, NJ, USA). The M-mode tracing and cine of three consecutive frames of 2-D parasternal short-axis views of the LV were simultaneously displayed in a split screen format. The 2-D cine was used as a reference image during M-mode measurements of LV dimensions. Measurements were obtained and the LV mass estimated according to the Penn convention. Interobserver variability for left ventricular internal dimension (LVID), interventricular septal thickness (IVS), posterior wall thickness (PWT), and left ventricular mass (LV mass) is low when either correlated (Pearson correlation coefficients of 0.94, 0.82, 0.75, and 0.93, respectively) or expressed as a percent of the mean (3.0%, 10.0%, 10.2%, and 8.9%, respectively). When read in a blinded fashion, interobserver variability (especially for LV mass) is small using digitized, simultaneously acquired and displayed cines of 2-D and M-mode echocardiograms. This is likely due to the ability to discriminate myocardial wall edges (endocardium) from other associated structures such as tricuspid and mitral apparatus. This method may prove useful in studies of LV mass.

THE RASSP INTEGRATED SYSTEMS TOOL SET PROVIDES BETTER SYSTEM TRADE‐OFF STUDIES

AbstractThe goal of the ARPA/Tri‐Service‐sponsored Rapid Prototyping of Application Specific Signal Processors (RASSP) program is to reduce development and manufacturing time and cost of signal processors by a factor of four. Lockheed Martin's Advanced Technology Laboratories (ATL) RASSP team has developed an integrated systems engineering tool set. This tool set integrates Ascent Logic's RDD‐100, PRICE Systems parametric cost estimation models, and Management Sciences RAM‐ILS tools. This tool set provides systems engineers with cost and reliability estimation data within a systems engineering tool. This tool set is described and an example of the tool usage provided. The example demonstrates the value of the tool integration. This tool set enables systems engineers to estimate the life‐cycle costs and reliability early in the design process.

頭蓋内腫よう病変の術中カラードプラ超音波の使用経験

Recently, noninvasive demonstration of major cerebral arteries has become possible by using transcranial color-coded duplex sonography. We carried out neurosurgical operations in 11 patients with brain tumor and in 1 patient with vascular malformation employing intraoperative Brightness mode (B-mode), color flow imaging and power Doppler imaging (CFI and PDI) to identify mass lesions and, the brain and vascular structure. Ultrasound imaging was performed with an Ultramark 9 HDI (Advanced Technology Laboratories, U.S.A.) using various kinds of scanning probe. Real-time monitoring of B-mode imaging aids in guidance when biopsy probes are applied for brain tumor biopsy as well as in the identification of the localization of tumor masses. CFI and PDI can also demonstrate major cerebral vessels and improve our understanding of the context of brain structure and pathological lesions. PDI was able to reveal slow flow at occult arteriovenous malformations, which failed to be depicted as flow vessels by angiography. In conclusion, intraoperative ultrasound imaging may be useful as a mean of real time monitoring and assists us in performing neurological operations safely.

Volumetric flow estimation in vivo and in vitro using pulsed-Doppler ultrasound

The measurement of volumetric blood flow in small vessels in vitro and in vivo poses a significant technological challenge. In this study, two pulsatile flow models were developed, one with a 3.2-mm lumen diameter and one with a 12.7-mm lumen diameter, to assess the accuracy of volumetric flow estimation of two pulsed-Doppler devices, a Crystal Biotech VF1 20-MHz system with either a cuff-mounted or a needlemounted probe and an Advanced Technology Laboratories Ultramark 9 High Definition Imaging ® system with a 5-MHz linear array transducer. The VF1 volumetric flow error was measured in the 3.2-mm phantom over a variety of pulsatile and continuous waveforms. The accuracy of the VF1 was also tested in porcine femoral and renal arteries. VF1 volumetric flow error ranged from 4.8% to 54.3% in the in vivo studies. The ATL demonstrated similar volumetric flow errors in the porcine femoral artery (∼3.2 mm diameter), but these errors were reduced to ≤ 17.4% in the 12.7-mm-diameter in vitro flow model.

The acoustic field of a pulsed Doppler diagnostic ultrasound system near a pressure-release surface

Extravasation of blood cells has been observed in the lungs of mice and monkeys exposed to pulsed ultrasound conditions comparable to diagnostic levels [Child etal., Ultrasound Med. Biol. 16, 817–825 (1990) and A. F. Tarantal and D. R. Canfield, Ultrasound Med. Biol. (in press)]. In order to understand the ultrasound exposure conditions under which damage occurs, lung was modeled as a simple interface from water to air. The acoustic pressure output of an Advanced Technology Laboratories Ultramark 9 High Definition ImagingR system with a 5-MHz linear array transducer in pulsed Doppler mode (4 MHz) was interrogated near the pressure release surface (≤3 mm) with a Marconi 0.5-mm bilaminar membrane-type PVDF hydrophone. For the nonlinear waveforms produced, peak negative pressures of 2.0 MPa measured in free filed were increased to 4.5 MPa due to constructive interference near the interface. The behavior of the pressure release surface was also simulated computationally as a low-pass filter with a 180° phase shift. The impulse response of the interface was constructed using experimentally measured spectra of the incoming and reflected waves. The pressure waveform was calculated as a function of position by superimposing the incoming and reflected waves and was compared to the hydrophone measurements. The implications of these observations on insitu acoustic exposure near lung will be discussed.

From the Manufacturers: Advanced Technology Laboratories Inc

From the Manufacturers: Advanced Technology Laboratories Inc

Changes in myocardial echo amplitude during reversible ischaemia in humans.

This study investigated the changes in regional myocardial ultrasonic backscatter, measured as myocardial echo amplitude, that occur during reversible myocardial ischaemia in humans. Left anterior descending coronary angioplasty was used to produce reversible myocardial ischaemia in human subjects. Regional myocardial echo amplitude was studied in the interventricular septum and left ventricular posterior free wall before, during, and after coronary occlusion with the angioplasty balloon. Wall motion analysis of the left ventricle was performed from simultaneous cross sectional echocardiographic imaging. Patients were studied prospectively. Six patients (mean age 56 (SD 11), range 46 to 69 years) with single vessel, left anterior descending coronary artery stenoses, were investigated during elective coronary angioplasty. A total of 11 balloon inflations were studied. All patient studies were performed at Harefield Hospital. Echo amplitude analysis was performed at the Royal Brompton Hospital. Angioplasty was performed by the usual procedure at Harefield Hospital for elective coronary angioplasty. All routine medication including beta blockers and calcium antagonists were continued. Inflation pressures were up to 12 atm (1212 kPa) and mean inflation time ranged from 30 to 120 (86 (31)) s. In four studies the first inflation was examined, in three the second, in two the third, and in one each the fourth and fifth inflations. Echo amplitude and cross sectional echo-cardiographic studies were recorded with a 3.5 MHz Advanced Technology Laboratories (ATL) (720A/8736 series) mechanical sector scanner and an ATL Mark III (860-1 series) echocardiograph system with 45 dB logarithmic grey scale compression. Regional echo amplitude was examined in four regions of the left ventricle--namely, the basal and mid-septum, and basal and mid-posterior wall. Consecutive end diastolic and end systolic frames were analysed and cyclic variation was determined as the difference between the level of echo amplitude at end diastole and at end systole. Measurements were made before balloon inflation, at peak inflation, and after balloon deflation. Regional wall motion and systolic wall thickening were analysed qualitatively. Before balloon inflation, cyclic variation in echo amplitude was noted in all regions (basal septum, 2.4 (SD 1.1) dB; mid-septum, 2.5 (1.1) dB; basal posterior wall, 3.3 (2.1) dB; mid-posterior wall, 3.9 (1.6) dB). During balloon inflation there was a significant fall in cyclic variation to 0.4 (0.9) dB (p < 0.0002) in the mid-septum. This was predominantly owing to an increase in end systolic echo amplitude from 5.4 (2.0) dB to 9.3 (1.9) dB (p < or = 0.01). This was associated with the development of severe hypokinesis or akinesis in the mid-septum. No significant changes in echo amplitude occurred in the three other regions examined. Changes were completely reversed after balloon deflation. These results suggest a causal relation between occlusion of the supplying coronary artery and blunting of myocardial echo amplitude cyclic variation. It is suggested that balloon occlusion produced myocardial ischaemia. The resultant impairment of myocardial contraction then caused a blunting of cyclic variation in echo amplitude. The results of this study provide further data about the ability of quantitative studies of ultrasonic backscatter to identify alterations in the myocardium during injury.

A new electronically enhanced biopsy system: value in improving needle-tip visibility during sonographically guided interventional procedures.

Sonographically guided fine-needle biopsy procedures are hampered by poor visibility of the needle tip. This study was performed to evaluate a new system for placing needles under sonographic guidance. The Biosponder needle (Advanced Technology Laboratories, Bothell, WA) incorporates a specialized stylet with a passive sensor at its tip. When an ultrasound pulse is detected by the sensor, an electrical signal is transmitted to the sonographic unit by a battery-powered electronic module connected to the stylet and to the scanner. This signal is converted into a bright, flashing marker on the screen at the precise location of the needle tip. The Biosponder system, which uses 20- or 22-gauge needles, was compared with a 20-gauge Turner needle (Cook, Bloomington, IN) in 18 patients with masses or fluid collections and two patients requiring nephrostomy tube placement. The tip of the Turner needle could not be localized precisely in any patient. The shaft of the Turner needle was seen clearly in 13 patients, poorly in three, and was not visualized at all in four patients. Excluding four instances of mechanical failure, the Biosponder system allowed precise localization of the needle tip in every patient and was consistently rated as easier to use than the Turner needle. We conclude that the Biosponder needle, with its precise tip localization and ease of use, is a valuable tool for sonographically guided needle placement.

Amplitude information from Doppler color flow mapping systems: A preliminary study of the power mode

The flow of a saline-glycerin solution with sand particles through a continuous in vitro flow system was imaged by using two commercially available Doppler color flow mapping systems in a power mode (Toshiba SSH-160A and Advanced Technology Laboratories [ATL] Ultramark 9). The images generated from seven solutions with particle concentrations ranging from 0.0001 × 1012to 6 × 1012particles/liter and a mean velocity of 30 cm/s measured with use of pulsed Doppler ultrasound were used to examine the dependence of the power mode on particle concentration.To examine the velocity dependence, 20 mean velocities ranging from 0.1 to 0.53 m/s (3 to 30 liters/min) and three particle concentrations (1, 3 and 6 × 1012particles/liter) in the solution were used. The recorded images were digitized and analyzed off-line. The SUM values, or the adjusted color intensity levels in delineated areas of interest in the displayed flow, were compared. In general, the power mode was sensitive in displaying slower velocity flows; in the selected particle concentration and velocity ranges, it was both velocity and concentration dependent. The specific dependence differed for the two color flow mapping systems.

Hysterosalpingography with color Doppler ultrasonography

To assess the accuracy of the diagnosis of tubal occlusion with the use of color Doppler flow ultrasonography and hysterosalpingography, 129 infertile women were studied. All 129 women had the procedure performed with an ATL Ultramark 9 (Advanced Technology Laboratories, Bothel, Wash.) color Doppler ultrasonography machine. Eighty-five of the 129 women also had an additional study including x-ray hysterosalpingography and/or chromopertubation. Of these 85 women, 58 had pelviscopic examination with chromopertubation. The frequency of diagnosis of tubal occlusion was compared among the three methods. When results of ultrasonography-hysterosalpingography were compared with those of x-ray hysterosalpingography and/or chromopertubation, 69 of 85 (81%) studies showed agreement, and 50 of 58 (86%) ultrasonography-hysterosalpingography findings agreed with observations at chromopertubation. The frequency of comparable findings between x-ray hysterosalpingography and chromopertubation is 75%. These data suggest that ultrasonography-hysterosalpingography is at least as accurate as x-ray hysterosalpingography in diagnosing tubal occlusion. In addition, ultrasonography-hysterosalpingography is safer and more cost-effective than x-ray hysterosalpingography and chromopertubation.

Space communications scheduler: A rule-based approach to adaptive deadline scheduling

Job scheduling is a deceptively complex subfield of computer science. The highly combinatorial nature of the problem, which is NP-complete in nearly all cases, requires a scheduling program to intelligently traverse an immense search tree to create the best possible schedule in a minimal amount of time. In addition, the program must continually make adjustments to the initial schedule when faced with last-minute user requests, cancellations, unexpected device failures, etc. A good scheduler must be quick, flexible, and efficient, even at the expense of generating slightly less-than-optimal schedules. The Space Communications Scheduler (SCS) is an intelligent rule-based scheduling system developed at GE's Advanced Technology Laboratories. SCS is an adaptive deadline scheduler, which allocates modular communications resources to meet an ordered set of user-specified job requests on board the NASA Space Station. SCS uses pattern-matching techniques to detect potential conflicts within a schedule, then resolves these conflicts through algorithmic and heuristic means. As a result, the system generates and maintains high-density schedules without relying heavily on backtracking or blind search techniques. SCS was designed to allocate communication devices on board the Space Station, but its general-purpose scheduling strategy is suitable for many common real-world applications.

Image quality or signal fidelity?: K.N. Bates, Advanced Technology Laboratories, Bellevue, WA 98007

In this paper, a systematic computational and theoretical study of the thermo-fluid-dynamics governing the flow above a heated horizontal rotating disc is presented. The fluid flow field is much more complex here as compared to von Kármán’s original solution (which took into account only the effect of disc rotation), and the effects of non-linear interaction between buoyancy and rotation are critically analysed here by studying the separate and combined roles of disc rotation and buoyancy on the fluid dynamic and heat transfer characteristics. The self-similarity of von Kármán’s flow field is lost, and the present paper establishes, for the first time, that the flow field above a heated rotating disc is divided into three distinct fluid dynamic regions. The three regions are demarcated by the loci of V̂z=0 and V̂r=0. In region 1 (R-1), V̂r is positive and V̂z is negative (such directions of the velocity components are characteristic of von Kármán’s flow or pure forced convection). In region 2 (R-2), V̂r is negative and V̂z is positive (such directions of the velocity components are characteristic of pure natural convection near a static disc surface). In region 3 (R-3), both V̂r and V̂z are negative. The forced convection results are obtained asymptotically at a large non-dimensional radius R within the region R-1 showing the dominance of forced convection mechanism, however, the fluid retains the signature of natural convection even at large values of R in the region R-3 where there is an inward radial velocity. Similarly, although a plume forms in the central portion of the disc where the solution is dominated by the effects of buoyancy, the fluid retains a signature of the disc rotation in the helical pathlines of fluid particles rising in the plume (whereas there is no swirl velocity present in pure natural convection above a static disc). The non-linear interaction between buoyancy and rotation results in several peculiar, rather non-intuitive, flow phenomena. Examples of such peculiarity include (i) the presence of a very sensitive spot on the upper boundary such that for a small change in this initial position the fluid pathlines may face drastically different final outcomes, (ii) the presence of a small portion near the centre of the disc where the fluid supplies energy to the disc, (iii) the effect of rotation on the rate of convective heat transfer being diminished by buoyancy over certain part of the disc while being enhanced over another part. This non-linear effect on Nusselt number is quantified here in terms of a Grashof number defined for mixed convection (Grmc).